Intellectual Merit: The project is devoted to theoretical investigations of the optical frequency comb's interaction with ultracold atomic and molecular systems. It is aiming at the development of quantum control methods to manipulate dynamics in ultracold gases, to create and control ultracold molecules and mitigate the attendant decoherence. A semiclassical theory of ultrafast, phase-locked pulse train interaction with multilevel systems will be developed, taking into account the decay and collisional dephasing in the framework of the Liouville von Neumann equations with relaxation. The objective is to understand the mechanisms of light-matter interaction at ultracold temperatures that involve two-photon Raman transitions, and to implement them in preparing desired superposition states and controlling ultracold dynamics, e.g., vibrational ladder climbing. The newly developed methods will contain elements that mitigate or prevent decoherence in the system. The focus will be on the studies of polar molecules, such as the KRb molecule, and atomic systems, e.g.,Rubidium-85 and Rubidium-87. The amplitude and phase modulation will be applied to the pulse trains that form optical frequency combs. Dressed state analysis will be performed to uncover the mechanisms of modulated combs' interaction with ultracold atoms and molecules, and to gain insights on quantum control of the dynamics, including the case when decoherence is present in the system. The completion of these investigations will advance knowledge about light-matter interactions at ultracold temperatures and will provide new methods of quantum control that are robust for experimental realization.
Broader Impact: Newly developed ultracold control methods are expected to advance and broaden fields of applications, from ultracold chemical reactions, to quantum information and quantum computation, to metrology. Graduate students will get involved in the proposed investigations through developing theoretical models, programming, collecting and interpreting data of numerical calculations. New findings on applications of optical frequency combs will be incorporated into the material of the graduate course "Methods of Quantum Control" which the PI has developed and teaches every other year. Within this course, students learn about the advanced quantum control methods based on the latest developments of laser technologies. All of this broadens opportunities for their career development. Collaboration with experimental groups at Stevens Institute of Technology and other universities will be initiated, aiming at implementing newly developed control methods in experimental investigations.